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(b) (ii), (iii) and (iv)
(c) (i), (iii) and (iv)
(d) (ii), (iii) and (iv)

Q. 4.The teacher instructed three students ‘A’, ‘B’ and V respectively to prepare a 50%
(mass by volume) solution of sodium hydroxide (NaOH). ‘A’ dissolved 50g of NaOH in
100 mL of water. ‘B’ dissolved 50g of NaOH in lOOg of water while Vdissolved 50g of
NaOH in water to make 100 mL of solution. Which one of them has made the desired
solution and why?

Q5 Which of the following correctly represents 360 g of water?

(i) 2 moles of H20
(ii) 20 moles of water
23
(iii) 022 x 10 molecules of water
(iv) 12044 x 10 molecules of water
25

(a) only (i) (b) (i) and (iv) (c) (ii) and (iii) (d) (ii) and (iv)

Q.6. Is it possible for the atom of an element to have one electron, one proton and no
neutron. If so, name the element.

Q.7. Write any two observations which support the fact that atoms are divisible.

Q.8. Why did Rutherford select a gold foil in his a-ray scattering experiment?

Q.9. In response to a question, a student stated that in an atom, the number of protons
is greater than the number of neutrons, which in turn is greater than the number of
electrons. Do you agree with the statement? Justify your answer.

Q.10. (a) Enlist the conclusions drawn by Rutherford from his α-ray scattering
experiment.
(b)In what way is the Rutherford’s atomic model different from that of Thomson’s atomic
model?

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